Naholo, who turned 28 yesterday, will join London Irish in the English Premiership. The club has just won promotion to the top tier of English club rugby.
Naholo has played 57 games for the Highlanders, after shifting from the Blues, and his dazzling form in his debut season in 2015 helped the Highlanders win their only title. He also won his way into the All Black squad for the World Cup.
The winger boasts 26 All Blacks test caps, and has scored 16 tries. He debuted for the All Blacks against Argentina in Christchurch in 2015 and overcame a leg injury to gain selection and play two matches in the 2015 Rugby World Cup in England.
Naholo is the Highlanders top try scorer with 41 to date, including a record 13 in 2015.
The Fijian has not played for a month after picking up a knee injury at training, but was hoping to be back this week or next. He has struggled this year and is yet to cross the tryline.
While glad he has secured his future with London Irish, Naholo said he was still 100% focused on his short-term goals.
''I'm looking forward to the opportunity of playing in the UK, but I'm still very much focused on the present and want to work really hard with the Highlanders to ensure we finish our season on a high,'' Naholo said.
''I feel like I owe it to the Highlanders after all that has happened to me since I came down here in 2015 - it really changed my life. I'm very appreciative of everything the club has done for me and our fans are the best in the world. I also have other goals I'd like to achieve with the All Blacks in 2019, and I know our Highlanders fans will be right behind me all the way.''
All Blacks head coach Steve Hansen said Naholo was a special member of the All Blacks group.
''He's an exciting player who brings an infectious sense of energy and humour to the team environment. While we look forward to seeing him in action in New Zealand in 2019, we wish him well for his future ventures.''